| Global warming is the increase in the average | | | | few individual scientists also disagree with parts of |
| temperature of the Earth's near-surface air and | | | | them. |
| oceans in recent decades and its projected | | | | An increase in global temperatures can in turn cause |
| continuation. | | | | other changes, including sea level rise, and changes in |
| Global average air temperature near the Earth's | | | | the amount and pattern of precipitation resulting in |
| surface rose 0.74 ± 0.18 °C during the past | | | | floods and drought. There may also be changes in the |
| century. The Intergovernmental Panel on Climate | | | | frequency and intensity of extreme weather events, |
| Change (IPCC) concludes, "most of the observed | | | | though it is difficult to connect specific events to global |
| increase in globally averaged temperatures since the | | | | warming. Other effects may include changes in |
| mid-20th century is very likely due to the observed | | | | agricultural yields, glacier retreat, reduced summer |
| increase in anthropogenic greenhouse gas | | | | streamflows, species extinctions and increases in the |
| concentrations," which leads to warming of the surface | | | | ranges of disease vectors. |
| and lower atmosphere by increasing the greenhouse | | | | The term "global warming" is a specific example of the |
| effect. Natural phenomena such as solar variation | | | | broader term climate change, which can also refer to |
| combined with volcanoes have probably had a small | | | | global cooling. In common usage the term refers to |
| warming effect from pre-industrial times to 1950, but a | | | | recent warming and implies a human influence. The |
| small cooling effect since 1950. | | | | United Nations Framework Convention on Climate |
| These basic conclusions have been endorsed by at | | | | Change (UNFCCC) uses the term "climate change" for |
| least 30 scientific societies and academies of science, | | | | human-caused change, and "climate variability" for |
| including all of the national academies of science of the | | | | other changes. The term "anthropogenic climate |
| major industrialized countries. The American | | | | change" is sometimes used when focusing on |
| Association of Petroleum Geologists is the only | | | | human-induced changes. |
| scientific society that rejects these conclusions, and a | | | | |